Introduction to the Digital BAS

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Introduction to the Digital BAS
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Overview

• What is the MAF/TIGER Database?
• What is included in the Digital BAS package?
• What is the difference between Digital BAS and
  MTPS?
• What are some tips for updating the BAS materials
  digitally?
• How do I return my digital submission to the
  Census Bureau?
• MTPS and Digital BAS Demo

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MAF/TIGER Database

• Master Address File/Topologically Integrated
  Geographic Encoding and Referencing (MAF/TIGER
  Database)
• Rather than having one layer for each feature
  class, all information is stored in a single
  layer
• Database is constructed of nodes, edges, and
  faces
• Each edge can represent the boundary for multiple
  geographies
• Place, County, Tract, School District, Voting
  District Boundaries, etc.
• Changing a place boundary can affect boundaries
  for other geographies

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Topological Relationship
Edges
Census Tract
Incorporated Place
School District
Integrated Layer
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MAF/TIGER Database - Edges
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MAF/TIGER Database County Subdivisions
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MAF/TIGER Database School Districts
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MAF/TIGER Database Voting Districts
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BAS Package Materials

• Letter and Form
• Contains your username for MTPS bas
• You do not need to fill out the form when
  responding digitally
• MAF/TIGER Partnership Software CD
• Data and Respondent Guide CD/DVD
• Contains shapefiles for use with Digital BAS and
  MTPS
• Contains respondent guides for Digital BAS and
  MTPS
• No Change postcard

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Digital BAS

• Participants use their own GIS to create the
  digital BAS submission file
• Create change polygons representing the
  difference between local boundaries and the
  Census Bureaus boundaries
• Attribute each polygon with the required
  information
• We send out ESRI shapefiles (.shp), but any GIS
  that can read/convert shapefiles may be used
• It is important to read the Digital BAS
  respondent guide carefully to make sure you
  include all required information

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MAF/TIGER Partnership Software - MTPS

• As an alternative to another GIS software,
  participants may use the Census Bureaus free
  MTPS to create the digital BAS submission file.
• The MTPS forces the user to include the required
  attribute information for the boundary and
  feature updates.
• The software handles the data conversion and
  compresses all of the output files together for
  you to create the final digital BAS submission
  file.
• MTPS is appropriate for users who are not
  experienced in GIS or do not have their own GIS
  software.

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Digital Update Guidelines

• We cannot accept a local GIS file to replace
  our existing boundary information
• Must have legal documentation and effective dates
  for all legal boundary changes
• We must keep record of all changes made for
  reference purposes
• Topologically integrated database
• Snap to existing census geography where
  appropriate
• Use existing census roads, rail, and hydro
  wherever possible (if our river and your river
  differ spatially by 10 feet, snap to our river)

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Data Projections

• Census files are in GCS NAD 83 format and can be
  projected into any local coordinate/projection
• Most GIS software packages will allow users to
  transform file coordinate systems and projections
• In ArcGIS, use the Project tool in ArcToolbox

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Types of Boundary Updates

• Annexations Deannexations
• Boundary Corrections
• Geographic Corridors Offsets
• New Incorporations

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Other Acceptable Updates

• Linear Features
• Point Landmarks
• Area Landmarks
• Address Ranges

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Annexations and Deannexations

• These are referred to as legal boundary changes
• Large change polygons are most likely annexations
• Change polygons are sometimes not contiguous with
  your boundaries
• A change to the entitys boundary through a legal
  action
• Ordinance/Resolution
• Local law or Court order
• State level action
• Must always include the following in lieu of the
  actual legal documentation
• Effective Date
• Ordinance/Resolution Number
• Acreage required for Georgia entities

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Annexations and Deannexations (Attribute Table)

• Must enter the following in the change polygon
  attribute table for each annexation/deannexation
• Name of the affected entity
• The effective date
• The document/authorization number (Ex ordinance
  or resolution )
• Change type is coded A for annexation or D for
  deannexation

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Boundary Corrections

• Minor fixes to the entity boundaries due to
  drafting or plotting errors.
• Should follow the general shape of the current
  boundary.
• Are neither annexations nor deannexations,
  although they may be fixing the depiction of
  previous annexations or deannexations.
• Boundary corrections DO NOT require legal
  documentation.

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Boundary Corrections (Attribute Table)

• Must enter the name of the affected entity in the
  Name field
• Enter B in the Change Type field to designate a
  Boundary Correction
• In the Relate field enter the following
• IN if the territory needs to be in the affected
  entity
• OUT if the territory needs to be out of the
  affected entity

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Geographic Corridors

• An area that only includes road surface and
  right-of-way and does not contain any structures
  addressed to either side of the road.
• The Census Bureau will geocode addresses based on
  the centerline of road.
• There are two types of geographic corridors
• 1.) Road through unincorporated space
• 2.) Road through incorporated space
• BAS participants should recommend the creation of
  a geographic corridor ONLY when this coding would
  result in addresses being assigned to the wrong
  entity.

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Geographic Corridors
Example Road through an unincorporated place In
this example, the houses are in unincorporated
county, while the road ROW has been annexed into
an incorporated place. Without a corridor, the
housing units along this road would be included
in the incorporated place.
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Geographic Offset

• An area claimed by an entity that is only on one
  side of the road and does not include any
  structures addressed to the right-of-way on that
  side of the road.
• Policy towards Geographic Offsets
• We prefer that you do not show a boundary on a
  front lot line.
• If houses on the far side of the road should be
  in your jurisdiction, please represent the
  boundary on the rear lot line.
• If houses on the far side of the road should NOT
  be in your jurisdiction, please snap the boundary
  to the centerline.
• An offset should be used if you must show the
  boundary on the front lot line.
• Using one of these techniques insures that the
  residential structures will be assigned to the
  correct geography.

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Geographic Corridors and Offsets Incorporated
Places
We prefer that you snap the boundary to the
centerline as offsets are difficult to maintain.
If offsets are not coded as such, your boundary
will be snapped.
A
B
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New Incorporations

• For all new incorporations, we need the
  following
• The official name of the new incorporation
• The name and phone number of a contact person for
  processing
• A copy of the official papers of incorporation
• The effective date
• The mailing address
• The name of the HEO of the new incorporation
• The name of the BAS contact of the incorporation,
  if different from the HEO

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Street Features

• Street features can be added or edited in MTPS or
  ArcGIS
• These are not required unless they serve as a
  boundary

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Data Dictionary
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Reporting the Data to the BAS

• Compress your change polygon shapefile and any
  other edited shapefiles into a zip file
• If you are using MTPS, the software will
  automatically zip the required shapefiles after
  you are done.
• Upload the zip file onto the Census Bureaus FTP
  site.
• Instructions for the site are provided in the
  Respondent Guides.
• The MTPS submission file can be quite large. If
  you are having issues uploading the file onto the
  FTP site, simply remove all the files that do not
  contain the BAS prefix in the name, and try
  uploading again.

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Digital BAS Demonstration ArcGISMAF/TIGER
Partnership Software (MTPS)